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Abstract:

A method of manufacturing an impeller including a substantially
disk-shaped disk, a cover facing the disk, and a blade provided between
the disk and the cover, the method includes: forming a groove in a blade
attachment surface of the disk or the cover so as to correspond to the
shape of an edge tip of the blade; and bonding an inner surface of the
groove to the edge tip of the blade through a bonding agent after
inserting the edge tip of the blade into the groove.

Claims:

1. A method of manufacturing an impeller including a substantially
disk-shaped disk, a cover facing the disk, and a blade provided between
the disk and the cover, the method comprising:forming a groove in a blade
attachment surface of the disk or the cover so as to correspond to the
shape of an edge tip of the blade; andbonding an inner surface of the
groove to the edge tip of the blade through a bonding agent after
inserting the edge tip of the blade into the groove.

2. The method according to claim 1, further comprising:disposing a bonding
agent so as to bond a side surface of the blade to the blade attachment
surface in the vicinity of the groove.

3. An impeller comprising:a substantially disk-shaped disk;a cover facing
the disk; anda blade provided between the disk and the cover,wherein the
blade is inserted into a groove formed in at least one of the disk and
the cover, and is bonded thereto through use of a bonding agent.

4. The impeller according to claim 3,wherein substantially semi-circular
recessed portions each having a circular-arc surface in a sectional view
are provided on both sides of the groove along the groove.

5. A compressor comprising the impeller according to claim 3 4.

6. A compressor comprising the impeller according to claim 4.

Description:

BACKGROUND OF THE INVENTION

[0001]1. Field of the Invention

[0002]The present invention relates to a method of manufacturing an
impeller used in a centrifugal rotary machine such as a centrifugal
compressor, an impeller, and a compressor having the impeller.

[0003]Priority is claimed on Japanese Patent Application No. 2009-022867,
filed Feb. 3, 2009, the content of which is incorporated herein by
reference.

[0004]2. Description of the Related Art

[0005]In the past, as an impeller used in a centrifugal rotary machine
such as a centrifugal compressor, there has been known a cover attachment
impeller (closed impeller) including a disk attached to a rotary shaft, a
cover disposed in the disk while having a gap therebetween, and plural
blades connecting the disk and the cover to each other. In the impeller,
a portion surrounded by a side surface of each blade and stream surfaces
of the cover and the disk is formed as a passageway used to compress air.
In addition, the impeller provided in the centrifugal compressor is
formed by, for example, integral forming performed by casting, machining,
or electric spark machining, or bonding performed by welding, brazing, or
liquid phase diffusion bonding after forging and mechanical machining.

[0006]Among them, the integral forming is to integrally form the cover,
the blade, and the disk by cutting a material. Incidentally, in general,
the impeller provided in the centrifugal compressor includes a passageway
formed in a complex shape in which the passageway is curved in the axial
direction (rotary shaft direction) and the radial direction. For this
reason, the integral forming is difficult.

[0007]In the bonding performed by welding, two parts, that is, an integral
member obtained by integrally forming the blade with one of the cover and
the disk through cutting and the other of the cover and the disk, are
bonded to each other through welding. Alternatively, the blade, the
cover, and the disk are bonded to each other through welding. In this
case, it is necessary to insert a welding torch inside the passageway.
Accordingly, when the passageway is narrow, it is difficult to insert the
welding torch into the passageway. As a result, welding defects may
easily occur.

[0008]Meanwhile, the bonding performed by brazing is known in, for
example, JP-A-2003-328989 (hereinafter, Patent Document 1) or
JP-A-H07-109997 (hereinafter, Patent Document 2). In the bonding
performed by brazing, for example, upon bonding the blade attachment
cover to the disk, filler metals such as foils, powders, or wires are
disposed in the connection portion, and the cover and the disk are
installed and heated in a furnace in a joining state so as to be bonded
to each other. Even when the passageway is narrow, the bonding performed
by brazing can be easily performed compared with the bonding performed by
welding.

[0009]In the method of manufacturing the impeller disclosed in Patent
Document 1, a plating layer is provided both in the combination of a
blade and a shroud (cover) and in a hab (disk). The hab provided with a
groove having an R-part in both sides thereof and the combination is
bonded to each other. Alternatively, a plating layer is provided both in
the combination of the blade and the hab and the shroud. The shroud
provided with a groove having an R-part in both sides thereof and the
combination is bonded to each other.

[0010]In the method of manufacturing the impeller disclosed in Patent
Document 2, a main-plate-side blade integrally formed with a hab (disk)
and a shroud-side blade integrally formed with a shroud (cover) are
bonded to each other through filler metal.

[0011]However, the method of manufacturing the impeller of the related art
has the following problems.

[0012]In the impeller provided in the centrifugal compressor, a tensile
force is generated in a direction in which the cover and the disk move
away from each other due to a centrifugal force with a rotation, and a
relative bending stress is generated in the rotation direction.
Accordingly, a large stress concentration is generated in a bonding
portion corresponding to a joint between the blade and the disk. For this
reason, in the case of the bonding performed by brazing, in order to
reduce the stress concentration, it is necessary to consider a solution
such that the brazing portion is formed in a fillet shape. However, as
described above, each passageway R is formed in a complex curve shape,
and the bonding line between the blade and either the disk or the cover
is formed as a complex three-dimensional curve. Accordingly, the melted
filler metal may flow outside during the brazing. That is, in this case,
the amount of the filler metal may be not sufficient in a part of the
bonding portion, or the filler metal may be lost, which may cause bonding
defects. Accordingly, it is not possible to ensure sufficient bonding
strength. For this reason, in the bonding performed by brazing, liquid
phase diffusion bonding, or the like, there is a demand for a method
capable of reliably improving the bonding strength.

[0013]The present invention is contrived in consideration of the
above-described problem, and an object of the present invention is to
provide a method of manufacturing an impeller capable of improving the
bonding strength between a blade and either a disk or a cover, an
impeller having a high bonding strength between a blade and either a disk
or a cover, and a compressor having an impeller.

SUMMARY OF THE INVENTION

[0014]In order to achieve the above-described object, according to an
aspect of the present invention, there is provided a method of
manufacturing an impeller including a substantially disk-shaped disk, a
cover facing the disk, a blade provided between the disk and the cover,
the method including: forming a groove in a blade attachment surface of
the disk or the cover so as to correspond to the shape of an edge tip of
the blade; and bonding an inner surface of the groove to the edge tip of
the blade through a bonding agent after inserting the edge tip of the
blade into the groove.

[0015]According to another aspect of the present invention, there is
provided an impeller including: a substantially disk-shaped disk; a cover
facing the disk; and a blade provided between the disk and the cover,
wherein the blade is inserted into a groove formed in at least one of the
disk and the cover, and is bonded thereto through use of a bonding agent.

[0016]With the above-described configuration, the groove is provided in
the blade attachment surface of the disk or the cover so as to correspond
to the shape of the edge tip of the blade, the bonding agent such as
filler metal is disposed in the groove or the bonding-side edge tip of
the blade, and then the edge tip of the blade is inserted into the groove
by heating the bonding agent so as to bond to each other through use of a
melted bonding agent. At this time, the bonding agent being in a liquid
state due to heating is hardened inside the groove, and the edge tip of
the blade is strongly fitted and bonded to the groove. In addition, since
it is possible to prevent the melted bonding agent from flowing outside
during the bonding operation, it is possible to prevent a problem such
that the amount of the bonding material is not sufficient in the bonding
portion.

[0017]The method having the above-described configuration may further
include: disposing a bonding agent so as to bond a side surface of the
blade to the blade attachment surface in the vicinity of the groove.

[0018]In this case, in addition to the bonding inside the groove, the side
surface of the blade and the blade attachment surface are bonded to each
other. Accordingly, it is possible to more reliably reinforce the bonding
portion between the disk or the cover and the blade applied with large
stress.

[0019]In the impeller having the above-described configuration,
substantially semi-circular recessed portions each having a circular-arc
surface in a sectional view may be provided on both sides of the groove
along the groove.

[0020]In this case, it is possible to alleviate the stress concentration
generated in the bonding portion between the blade and either the cover
or the disk during the rotation of the impeller. Particularly, since the
edge tip of the groove is close to the side surface of the blade so as to
be smoothly continuous thereto, it is possible to increase the advantage
of reducing the stress concentration.

[0021]In the method of manufacturing the impeller and in an impeller
having the above-described configuration, the bonding agent melted by
heating is disposed inside the groove provided in the disk or the cover,
and the bonding agent being in a liquid state by heating is hardened
inside the groove so that the edge tip of the blade is tightly fitted and
bonded to the groove. Accordingly, it is possible to reliably improve the
bonding strength between the blade and either the cover or the disk.

[0022]The compressor according to still another aspect of the present
invention includes an impeller having a high bonding strength between the
blade and the disk or the cover manufactured by the method of
manufacturing the impeller according to an aspect of the present
invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is a side sectional view showing a schematic configuration of
an impeller manufactured by a method of manufacturing an impeller
according to a first embodiment of the present invention.

[0024]FIG. 2 is a partially enlarged view showing an impeller in FIG. 1.

[0025]FIG. 3 is a schematic side view showing the impeller in FIG. 2 when
seen from the outer peripheral side thereof.

[0026]FIG. 4A is a view showing a state before brazing in an impeller
manufacturing process.

[0027]FIG. 4B is a view showing a state after the brazing in the impeller
manufacturing process.

[0028]FIG. 5 is a schematic side view showing the impeller according to a
first modified example of the first embodiment of the present invention
when seen from the outer peripheral side thereof.

[0029]FIG. 6 is a schematic side view showing the impeller according to a
second modified example of the first embodiment of the present invention
when seen from the outer peripheral side thereof.

[0030]FIG. 7 is a schematic side view showing the impeller according to a
third modified example of the first embodiment of the present invention
when seen from the outer peripheral side thereof.

[0031]FIG. 8 is a schematic side view showing the impeller according to a
fourth modified example of the first embodiment of the present invention
when seen from the outer peripheral side thereof.

[0032]FIG. 9 is a schematic side view showing the impeller according to a
second embodiment of the present invention when seen from the outer
peripheral side thereof.

[0033]FIG. 10 is a schematic side view showing the impeller according to a
modified example of the second embodiment when seen from the outer
peripheral side thereof.

DETAILED DESCRIPTION OF THE INVENTION

[0034]Hereinafter, a method of manufacturing an impeller and an impeller
according to a first embodiment of the present invention will be
described with reference to FIGS. 1 to 4A and 4B.

[0035]FIG. 1 is a side sectional view showing a schematic configuration of
an impeller manufactured by a method of manufacturing an impeller
according to a first embodiment of the present invention. FIG. 2 is a
partially enlarged view showing an impeller in FIG. 1. FIG. 3 is a
schematic side view showing the impeller in FIG. 2 when seen from the
outer peripheral side thereof. FIG. 4A is a view showing a state before
brazing in an impeller manufacturing process. FIG. 4B is a view showing a
state after the brazing in the impeller manufacturing process.

[0036]The reference numeral 1 in FIG. 1 indicates an impeller manufactured
by the method of manufacturing the impeller according to the first
embodiment. The impeller is a rotary body which is assembled to a rotary
shaft, and is mounted to a compressor such as a centrifugal compressor.

[0037]As shown in FIGS. 1 and 2, the impeller 1 includes a substantially
disk-shaped disk 2 which is coaxially attached to a rotary shaft (not
shown), plural vane-shaped blades 3, each of which has one end fixed onto
the disk 2 and which are radially disposed about the axis O of the rotary
shaft, and a cover 4 which is disposed to face the disk 2 while being
distant therefrom and is fixed to the other end of each blade 3. In
addition, a space formed between a side surface of the blade 3 and a
stream surface (surfaces facing each other) between the disk 2 and the
cover 4 serves as a passageway R of a gas used to compress the
compressor.

[0038]The right side on FIG. 2 is set to the inner peripheral side (the
side of the axis O shown in FIG. 1) of the impeller 1, and the left side
is set to the outer peripheral side. In FIGS. 1 and 2, in a gas flowing
direction (a direction indicated by the arrow E) inside the passageway R,
the upper side is set to the upstream side, and the lower side is set to
the downstream side. The rotary shaft direction of the impeller 1 is set
to the Y direction, and the radial direction thereof is set to the X
direction. Hereinafter, the directions will be consistently used.

[0039]The disk 2 is used to form the outer shape of the impeller 1, and is
formed of metal such as carbon steel or stainless steel. The disk 2
includes a cylindrical portion 21 into which the rotary shaft (not shown)
is fitted and a body portion 22 which extends from one end (that is, the
lower side on FIGS. 1 and 2) of the cylindrical portion 21 in the rotary
shaft direction Y toward the outer peripheral side in the radial
direction X, where the cylindrical portion 21 and the body portion 22 are
integrally formed with each other. Here, it will be described hereinafter
on the assumption that the upper surface (on the side of the passageway R
of the gas), facing the cover 4, of the disk 2 shown in FIGS. 1 and 2 is
set to a front surface 2a, and the opposite lower surface thereof is set
to a rear surface 2b. The front surface 2a of the body portion 22 is
formed in a curve shape which gradually protrudes toward a front end 21a
of the cylindrical portion 21 in the rotary shaft direction Y in a
direction from the outer peripheral side to the inner peripheral side.

[0040]As shown in FIGS. 2 and 3, the front surface 2a of the disk 2 is
provided with a groove 5 which corresponds to an edge tip 3a of the blade
3 on the side of the disk 2, and has a thickness slightly larger than
that of the blade 3. In addition, in this embodiment, filler metal 6
(bonding agent) such as powder or wire is disposed on a bottom portion 5a
(groove inner surface) of the groove 5 so as to bond the blade 3 to the
disk 2 by brazing. In addition, the depth of the groove 5 is, for
example, equal to or more than 1 mm and equal to or less than 2 mm. In
the case where the depth of the groove 5 becomes deeper, the amount of
the filler metal 6 increases. For this reason, it is desirable that the
depth of the groove 5 is shallow.

[0041]Each blade 3 provided between the disk 2 and the cover 4 is smoothly
curved so as to protrude toward the front end in the rotary shaft
direction (the direction indicated by the arrow Y) as it becomes closer
to the inner peripheral side in the radial direction (the direction
indicated by the arrow X) along the front surface 2a of the disk 2, and
is curved toward one side of the disk 2 in the circumferential direction.

[0042]A lower surface 4a of the cover 4 is integrally fixed to a
cover-side bonding end 3b of the blade 3, and the cover 4 is formed in a
curve shape which protrudes toward the front end in the rotary shaft
direction Y in a direction from the outer peripheral side to the inner
peripheral side in the radial direction (the direction indicated by the
arrow X).

[0043]That is, as described above, the passageway R is formed between the
adjacent blades 3 so as to generate compressed air with the rotation of
the impeller 1. The passageway R is formed in a curve shape in the rotary
shaft direction Y and the circumferential direction along the shapes of
the disk 2, the blade 3, and the cover 4.

[0044]In the case where the impeller 1 of the compressor having the
above-described configuration is rotationally driven about the axis O by
a driving unit (not shown), the air stream is generated, and the air is
accelerated by the centrifugal force generated by the rotation, where the
air stream is indicated by the arrow E facing from the inner peripheral
side to the outer peripheral side in the radial direction in the
passageway R. Accordingly, the air sucked into an inlet R1 of the
passageway R is compressed inside the passageway R and is discharged from
an outlet R2. Subsequently, the air is sent to an external device (not
shown) on the downstream side.

[0045]Next, the method of manufacturing the impeller 1 will be described.
First, as shown in FIG. 4A, the groove 5 is formed in a blade attachment
surface (front surface 2a) of the disk 2 so as to correspond to the shape
of the blade 3, and as shown in FIG. 2, the cover 4 is integrally formed
with the plural blades 3 by cutting a material.

[0046]Subsequently, the filler metal 6 is disposed throughout the bottom
portion 5a of the groove 5, and as shown in FIG. 4B, the edge tip 3a of
the blade 3 is inserted into the groove 5 so that the inner surface of
the groove 5 is bonded to the edge tip 3a of the blade 3 through the
filler metal 6. In detail, when the filler metal 6 interposed between the
blade 3 and the groove 5 of the disk 2 is heated while applying, for
example, a compressing force thereto, the filler metal 6 is melted, and
the liquid-state filler metal 6 is uniformly distributed throughout the
gap between the groove 5 and the blade 3, thereby bonding the disk 2 to
the blade 3. That is, since the groove 5 is provided, the filler metal 6
being in a liquid state by heating is hardened inside the groove 5, and
the edge tip 3a of the blade 3 is fitted to the groove 5. Accordingly, it
is possible to strongly bond them to each other. Further, since the
melted filler metal 6 does not flow outside from the groove 5 during the
bonding operation, it is possible to prevent a problem of the amount of
the filler metal 6 not being sufficient due to the outflow of the filler
metal 6.

[0047]In the method of manufacturing the impeller and the compressor
according to the first embodiment, since the filler metal 6 melted by
heating is disposed inside the groove 5 provided in the disk 2, the
filler metal 6 being in a liquid state by heating is hardened inside the
groove 5, and the edge tip 3a of the blade 3 is tightly fitted and bonded
to the groove 5. Accordingly, it is possible to reliably improve the
bonding strength between the disk 2 and the blade 3.

[0048]Next, another embodiment and modified examples will be described
with reference to the accompanying drawings. Since the same reference
numerals will be given to the same constituents as those of the first
embodiment, the description thereof will be omitted, and a configuration
different from that of the first embodiment will be described.

[0049]FIG. 5 is a schematic side view showing the impeller according to a
first modified example of the first embodiment of the present invention
when seen from the outer peripheral side thereof.

[0050]As shown in FIG. 5, the filler metal 6 is disposed in the bottom
portion 5a (see FIG. 3) of the groove 5 in the first embodiment, but in
the first modified example, instead of that position, the filler metals 6
are respectively disposed in both side surfaces (groove inner surfaces)
5b and 5b of the groove 5 formed in the disk 2. Even in this case, as in
the first embodiment, the groove 5 is formed in the disk 2 in advance,
and the edge tip 3a of the blade 3 integrally formed with the cover 4
(see FIG. 2) is inserted into the groove 5, thereby bonding the disk 2 to
the blade 3 through the filler metals 6.

[0051]FIG. 6 is a schematic side view showing the impeller according to a
second modified example of the first embodiment of the present invention
when seen from the outer peripheral side thereof.

[0052]As shown in FIG. 6, in the second modified example, in the state
where the blade 3 is inserted into the groove 5 having the filler metal
6a disposed in the bottom portion 5a, filler metals (bonding agents) 7
are respectively disposed in even attachment corner portions 3c
corresponding to the base portion of the blade 3 on the side of the disk
2. That is, in addition to the bonding inside the groove 5, the front
surface 2a of the disk 2 forming the blade attachment surface in the
vicinity of the groove 5 is bonded to the side surfaces of the blade 3
through the filler metals 7, thereby more reliably reinforcing the
bonding portion between the blade 3 and the disk 2 applied with the
largest stress during the rotation of the impeller.

[0053]FIG. 7 is a schematic side view showing the impeller according to a
third modified example of the first embodiment of the present invention
when seen from the outer peripheral side thereof. FIG. 8 is a schematic
side view showing the impeller according to a fourth modified example of
the first embodiment of the present invention when seen from the outer
peripheral side thereof.

[0054]In the third modified example shown in FIG. 7, substantially
semi-circular R grooves (recessed portions) 8A and 8B each having a
circular-arc surface in a sectional view are provided on both sides of
the groove 5 of the disk 2 along the groove 5. Since the R grooves 8A and
8B are provided, it is possible to exhibit a function of alleviating
stress concentration caused by the blade 3 during the rotation of the
impeller. The diameter or depth of each circular-arc surface of the R
grooves 8A and 8B is determined in accordance with the thickness of the
disk 2. In addition, it is desirable that the advantage of the stress
alleviation function becomes larger as the distance t between each of the
R grooves 8A and 8B and the side surface of the blade 3 fitted to the
groove 5 becomes smaller.

[0055]That is, as in the fourth modified example in FIG. 8, when the
distance t becomes minimal, the reinforcing filler metals 7 respectively
disposed on the attachment corner portions 3c of the blade 3 with respect
to the disk 2 are smoothly and continuously distributed in the edge tips
of the circumferential surfaces of the R grooves 8A and 8B, and the
connection surface is formed as a continuous curve surface. Accordingly,
it is possible to increase the advantage of reducing the stress
concentration generated in the bonding portion during the rotation of the
impeller.

[0056]FIG. 9 is a schematic side view showing the impeller according to a
second embodiment of the present invention when seen from the outer
peripheral side thereof.

[0057]In the second embodiment shown in FIG. 9, the width D1 of a groove
5A formed in the disk 2 is set to be smaller than the width D2 of the
blade 3, and a protruding portion 3d is formed in the disk edge tip 3a of
the blade 3 so as to be fittable to the corresponding groove 5A. In
addition, filler metals indicated by the reference numeral 6A is disposed
in the bottom portion 5a of the groove 5A, and filler metals indicated by
the reference numeral 6B are respectively disposed in groove edges 2c of
the front surface 2a of the disk 2 located on both sides of the groove
5A. That is, the groove edges 2c of the disk 2 are respectively bonded to
stepped surfaces 3e formed by the protruding portions 3d of the blade 3
through the filler metals 6B.

[0058]FIG. 10 is a schematic side view showing the impeller according to a
modified example of the second embodiment when seen from the outer
peripheral side thereof.

[0059]In the modified example (fifth modified example) of the second
embodiment shown in FIG. 10, the R grooves 8A and 8B according to the
third and fourth modified examples are provided in the structure
according to the second embodiment. The edge tips of the circular-arc
surfaces of the R grooves 8A and 8B on the side of the blade 3 are
respectively smoothly continuous to the side surfaces of the blade 3.
Accordingly, it is possible to more effectively alleviate the stress
concentration generated in the bonding portion between the disk 2 and the
blade 3.

[0060]As described above, although the method of manufacturing the
impeller and the impeller according to the first and second embodiments
and the first to fifth modified examples of the present invention are
described, the present invention is not limited to the above-described
embodiments and modified examples, but may be appropriately modified
within the scope without departing from the spirit of the present
invention.

[0061]For example, in the above-described embodiments and modified
examples, the blade attachment surface as the front surface 2a of the
disk 2 is provided with the groove 5, but the present invention is not
limited thereto. For example, the disk 2 and the blade 3 may be
integrally formed in advance, the groove may be formed in the blade
attachment surface of the cover 4 so as to correspond to the blade, and
then the blade 3 integrally formed with the disk 2 may be inserted and
bonded to the groove through the filler metal 6.

[0062]In the above-described embodiments and modified examples, the
bonding operation is performed by the brazing, but the present invention
is not limited thereto. For example, liquid phase diffusion bonding may
be used.

[0063]In the above-described embodiments and modified examples, the
bonding method is used which disposes the filler metal 6 in the groove
inner surface (the bottom portion 5a and the side surface 5b) on the side
of the disk 2, and inserts and bonds the edge tip 3a of the blade to the
groove 5, but the present invention is not limited thereto. That is, in
the state where the filler metal 6 is disposed in the edge tip 3a of the
blade without disposing the filler metal 6 in the groove 5, the edge tip
3a of the blade may be inserted and bonded to the groove 5.

[0064]In addition, the shapes, sizes, and the like of the disk 2, the
blade 3, and the cover 4 may be arbitrarily set. Further, the depth and
width of the groove 5, the dimension of the R grooves 8A and 8B, and the
like may be arbitrarily set depending on the conditions.

[0065]While preferred embodiments of the present invention have been
described and illustrated above, it should be understood that these are
exemplary of the present invention and are not to be considered as
limiting. Additions, omissions, substitutions, and other modifications
can be made without departing from the spirit or scope of the present
invention. Accordingly, the present invention is not to be considered as
being limited by the foregoing description, and is only limited by the
scope of the appended claims.

Patent applications in class Blade held between separable surfaces

Patent applications in all subclasses Blade held between separable surfaces